NUMERICAL PARAMETRIC STUDY FOR OPTIMAL DESIGN OF DISCONNECTED PILED RAFT FOUNDATION

Disconnected piled raft (DPR) foundation is an innovative solution for sites with poor soil conditions where a conventional raft foundation may not provide a suitable foundation system. In the DPR system, the raft’s efficiency is enhanced by incorporating a limited number of disconnected piles, which primarily serve as settlement-reducing elements. A flexible cushion layer is inserted between the raft and the piles to create more uniform stress distribution under the raft. In this research, the performance of the DPR foundation on loose sand soil subjected to vertical loading is investigated through a comprehensive parametric study. 3D finite element analyses employing PLAXIS software are utilized to model the complex interactions within the DPR foundation. The piles and raft are represented as volume elements. The soil response is simulated with the Hardening Soil (HS) approach, which accurately captures the nonlinear elasto-plastic response and the stress-dependent stiffness of the soil. The study examines the effects of cushion thickness, cushion elastic modulus, pile length, and pile diameter on the load-settlement behavior of the DPR foundation, load sharing between the raft and the piles, as well as the axial loads and bending moments experienced by the floating disconnected piles. The findings from this study could be helpful in providing guidelines to achieve the optimal design of the DPR foundation resting on loose sand.